There's other factors though.
I've been playing around the duelist bracket for many seasons and i consistently face the same problems, a lot of people around 2k-2300 tends to develop a massive ego trips wich means they just won't queue with anyone they don't consider "worthy" wich greatly limits their practice sessions, they also tend to sit their rating forever to either get rewards as they're scared to tank or simply out of pride to not drop below what they consider "good" rating (usually milestones such as 2k and 2200), on top of that, most of those players actually stop improving there because they start to think they're too good to lose, some comes into play the endless amount of excuses on how the game is shit, how whatever comp beat them is skilless, how XYZ class is OP etc and they start raging and disbanding teams/dropping partners if they ever lose to teams they don't consider "worthy" based on above criterias, then they start the process all over again with other people. All of this completly shuts down any possibilities for self analysis required to improve your play.
Repped. I agree completely. You get better simply by playing more, most of the time. Stop caring so much about your rating, and care about improving, and rating tends to follow after a while.
Also, I'm of the firm belief that it's the losses that make you improve, not the wins.